1. Field of the Invention
The invention relates to clamps for surgical procedures and, more specifically, to a clamp assembly especially useful for clamping the ascending aorta during cardiac surgery.
2. Description of the Prior Art
During the course of cardiac surgery in which cardiac function is arrested, it is necessary to isolate the heart and coronary blood vessels from the remainder of the circulatory system. Circulatory isolation of the heart and coronary blood vessels is usually accomplished by placing a mechanical cross clamp externally on the ascending aorta downstream of the ostia of the coronary arteries, but upstream of the brachiocephalic artery so that oxygenated blood from the cardiopulmonary bypass system reaches the arms, neck, head, and remainder of the body. Using conventional techniques, the sternum is cut longitudinally (a median sternotomy) thereby providing access between opposing halves of the anterior portion of the rib cage to the heart and other thoracic vessels and organs. Alternatively, a lateral thoracotomy is formed, wherein a large incision is made between two ribs and the ribs are retracted. A portion of one or more ribs may be permanently removed to optimize access.
Regardless of whether a sternotomy or a thoracotomy is performed (both collectively referred to herein as a “gross thoracotomy”), the opening in the chest wall must be large enough to permit a cross clamp to be placed externally on the ascending aorta, thereby isolating the heart and coronary arteries from the remainder of the arterial system. A problem with existing cross clamps is their excessive size. A cross clamp usually includes a clamping portion from which integral actuating handles project. The clamp occupies a relatively large portion of the operative site, thereby requiring that the sternum or ribs be retracted to a greater extent than is desired. This is a significant factor in open-chest surgery, because the trauma caused by creating large openings in the chest wall often entails weeks of hospitalization and months of recuperation time.
Recently, techniques have been developed to facilitate the performance of cardiac procedures such as heart valve repair and replacement, coronary artery bypass grafting, and the like, using minimally invasive techniques that eliminate the need for a gross thoracotomy. Coronary artery bypass grafting, heart valve repair and replacement, and other procedures can be performed through small incisions or cannulae positioned in the chest wall. In one recently developed technique, a clamp is introduced into the patient's thoracic cavity through a percutaneous intercostal penetration in the patient's chest, typically using a trocar sleeve. The clamp is detachably mounted to the distal end of a clamp positioner. After the clamp is positioned around the ascending aorta, the clamp is actuated from outside the patient's thoracic cavity to squeeze the aorta and partially or completely block fluid flow therethrough. The clamp then is disengaged from the distal end of the clamp positioner and the clamp positioner is removed from the thoracic cavity to provide enhanced access to the region in question.
Although the referenced device permits cardiac surgery to be conducted with significantly smaller openings formed in the chest wall, there is a concern about the reliability of the clamp and whether a connection can be reestablished between the clamp and the clamp positioner when it is necessary to remove the clamp. A failure of the clamp or the inability to remove the clamp could have disastrous consequences for the patient.
Despite the advantages of minimally invasive cardiac surgery, certain situations still call for the use of a gross thoracotomy. In such circumstances, there remains a need for an aorta cross clamp that is smaller than existing cross clamps but which is extremely reliable and easy to use. In those cases where minimally invasive surgery is indicated, there is a need for an aorta cross clamp that is easy to apply to the ascending aorta, which is reliable in use, and which can be removed without fail.